Introduction: Cardboard Space Igloo for Cats (+ Spacepod Inspiration)


An enriched environment is important for the health and well-being of any animal--including humans. It can provide physical and mental stimulation through design challenges, strategic thinking and planning, and novel experiences in general. It also provides something for your cat to play in.

My first cardboard enclosure for my cat Amelia was an elongated “dodecahedron” (or space igloo). Eventually I got carried away and built her a retrofuturistic spacepod (see last step). This instructable details the process of building a space igloo and includes measurements.

Whether your cat ends up with gothic spires and pointed arches or the bold structural frames of monumental modernism, keep in mind that once you've finished your architectural masterpiece they may still prefer that empty wine box.

Step 1: Materials and Tools

You can build a light and strong structure quickly and easily with only hot glue and cardboard. The good thing is if you make a wrong cut or glue the wrong thing, it's easy to fix.


Lay your hands on the thickest cardboard you can find. This makes glueing joins easier and will make the entire structure more stable. Avoid thin single layer cardboard like cereal boxes. I'm using thick double-walled cardboard so Amelia's spacepod could probably survive re-entry into the atmosphere.

Similar to wood, cardboard 'grain' matters. There is likely a technical term for cardboard grain but for the sake of expediency I'm going to call it 'longways grain' and 'crossways grain' (see image). Cut your lengths of cardboard so that the grain runs longways, rather than crossways, as this will increase the strength of your structure.

Hot glue gun and lots of glue sticks

Generally a more expensive glue gun will heat glue to higher temperatures than cheap ones. This means you have longer to play with placement of the cardboard and end up with a stronger bond. If you are using a small craft glue gun, try and stick the pieces of cardboard together as fast as possible before the glue cools. The quality of the glue will also determine how well joins hold.

    A cutting mat or board

    Cutting mats are excellent to work on. They provide accuracy and control when cutting cardboard. Here I’m using a piece of MDF wood. The important thing is that there is some give in the surface so you don't dull the blade (and you don't cut into the dining table).

    A sharp blade

    NOTE: Be careful when cutting. Utility knives are extremely sharp and humans are soft. I still manage to cut myself from time to time. Here are some things to keep in mind when using a knife:

    • Cut in slow, steady strokes -- don't rush;
    • Only cut when you feel in control of the knife -- don't cut in awkward or difficult positions;
    • Use a solid knife that has a blade that doesn't rattle, slip or move.

    STANLEY KNIVES (fixed blade)

    Solid friends are Stanley knives. The blades do not slip. They do not bend. They do not damage easily. The tiny sharp point on the tip doesn’t even snap off that often. Stanley knives are excellent for cutting through thick, tough material. The fixed blade Stanley knife is my instrument of choice.


    You can get these quite cheap (although it's best to avoid to absolutely lowest costing ones as they can get a bit dodgey). If you use one of these, get one that has a slide-back locking mechanism that prevents the blade from slipping back into the handle (those with tightening screws or no lock at all can be dangerous).


    Pen knives are great for small details but not ideal for cutting thick cardboard.

    A ruler and a tape measure

    Use a ruler (or piece of hard, straight wood) that you are able to hold securely.

    Step 2: Igloo Walls

    Measurements are in millimetres.

    Sketch out one of the igloo walls. If you base the size of the panels on the amount of cardboard you have available, it will reduce wastage. Just make sure your cat will fit inside the end product!


    Push down hard when cutting so the ruler doesn’t slide around. You can even add something non-slip, i.e., thin rubber or blu-tak, to the underside of the ruler to reduce slippage. Make your marks and lines on the crappiest looking side of the cardboard so that you can have the best side facing out.

    Keep the knife blade perpendicular to the cutting surface (unless cutting mitred joins - see below) and tilt the handle towards you about 30-45 degrees. Slowly draw the blade towards yourself in steady strokes, making sure your fingers, and anything else that you don’t want cut, are out of the way.

    Don't worry if you make a mistake, bad cuts can be easily fixed with hot glue.

    Once you have one panel cut out, you can trace around it for the others. If you line up sides of the panels adjacent to each other, you will waste less cardboard.

    Cut out 10 panels (you actually only need 9 but 10 will make life easier later).

    Step 3: Mitred Joints

    Mitred joints can be a little tricky to get the hang of but they are worth it. Basically the angle that you cut the edge of the cardboard will determine the angle at which the pieces of cardboard are joined. For example, 45 degree mitred edges will result in the pieces of cardboard being at right angles to one another. See the difference between joining two pieces at right angles without a mitre, and joining two pieces with a mitre (at a more obtuse angle).

    Don't stress too much as cardboard is soft and flexible, so your angles don't have to be exact.

    We actually want a 54 degree mitre for our dodecahedron but I'll describe a 45 degree mitre because for all intents and purposes, 45 degrees will work fine. Draw a line parallel to the edge of the cardboard that is about the same distance from the edge as the cardboard is thick. For example, the cardboard I'm using is about 6.5 mm thick so my line is 6.5 mm from the edge.

    Then hold a ruler tight along the line and slightly tilt your knife over to the side (ideally at 45 or 54 degrees). Slowly and carefully draw the blade along the ruler, only cutting about 1-2 mm into the cardboard the first time. Cut a little deeper with each stroke, keeping your knife tilted. Take your time and make about 6-7 cuts.

    Cut 54 (or 45) degree mitres for the sides of the panels that don't intersect. For the sides that do intersect in a point, cut the angles steeper because we want the angle of these joins to be more obtuse. Don't mitre the sides that are opposite to the point as those sides will glue flat to the ceiling and base.

    Run hot glue along the edge of one of the non-intersecting sides and then place it together with another non-intersecting side. Hold the two pieces together for at least one minute. Be patient and make sure the glue has cooled sufficiently before letting go.

    Do this for five panels.

    Step 4: Ceiling

    Once five panels are glues together, place the non-spikey end onto a piece of cardboard and trace around it. This will be the ceiling. The pentagon may not be 'square' (i.e., all side and angles are exact) so it helps to make a mark on one side of the pentagon so that when you cut it out and glue it on, it is the same size and shape. Glue the pentagon onto the top of your walls. This is when is pays to be quick with a small glue gun as you won't have long before the glue cools.

    Note: The ceiling will have five walls, however the base will only have four as you need to leave a panel out for the entrance.

    Step 5: Remaining Walls and Base

    You can now add the remaining four mitred wall panels one at a time, leaving one panel off.

    This is where the tenth panel comes in handy. Cut a strip about 50 mm wide off the side that is opposite to the point. Glue this strip across the bottom of the igloo. This will make the structure more 'square'.

    If you just want a basic pod, you can repeat the steps for the ceiling and glue another pentagon to the base. Again make sure you mark which side will face the entrance so the base fits exactly.

    I wanted a tunnelled entrance so I traced the base pentagon and added a rectangle walkway.

    Step 6: Tunnel Entrance

    This part took a bit of trial and error due to the tilt of the opening so my dimensions may not exactly work for you. It's best not to make the angle too acute to start with as you can always slice off more little by little until the walls fit snugly.

    The same goes for the tunnel roof. Measure the sides and cut a piece of cardboard accordingly. Err on the side of making the angle too obtuse and then shave it down to the right fit.

    Step 7: Inspiration - Amelia's Spacepod

    Hopefully building a space igloo will equip you with the skills to get more creative. I've included pictures of Amelia's spacepod as inspiration.

    Have fun!

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